1. Field of Invention
This invention relates to electronic typewriters having a shiftable carriage mounting a printing head thereon and a paper feed device, for feeding a printing paper, based on operation of various keys arranged on a keyboard so as to perform the printing onto the paper.
2. Description of Prior Art
In prior electronic typewriters, a paper is fed so that in an in-line feed operation caused by depressing a carriage return key, a space is provided between printing lines, with characters, symbols and the like, printed thereon. Thus, disadvantageously, even if vertical lines are printed simply in the same column extending in a plurality of printing lines, a continuous long vertical line cannot be obtained, because of the space between the printing lines.
In order to eliminate such a disadvantage, the following method has been suggested in the art. First, a vertical line key on a keyboard is depressed, whereby one vertical line is printed at a desired position. Then, if necessary, desired characters, symbols and the like are key entered and printed continuously on the printing line. Next, the carriage return key is depressed to cause the paper to be fed by one printing line, and the carriage is returned to the left margin position so as to start the printing at the next printing line. Then, if necessary, desired characters, symbols and the like, are key entered and printed again. When the print head is moved to the position of the vertical line printed in the previous printing line, in order to connect the next vertical line to be printed with the previously printed vertical line, a superscript key or the like is operated, thereby to reverse feed the paper by a space which is less than the feed amount in the normal line feed operation.
The relative position between the print head and the paper is specified in the above manner, and then the vertical line key is depressed so as to print the vertical line. A subscript key or the like is operated, whereby the paper is fed in the forward direction by a space less than the feed amount in the normal feed operation, in order to connect the next printed vertical line with the previously printed vertical line. Then, the vertical line key is depressed so as to print the vertical line. In general, the carriage is shifted to the right by an amount corresponding to one character each time the printing is performed. In this state, the back space key is depressed so as to shift the carriage backwards by an amount corresponding to one character. Then, the subscript key is operated again to cause the paper feed to be performed as above.
If the paper is not fed to a position whereat the paper reverse feed is started by operating the superscript key, the short paper feed and the vertical line printing are alternately performed further as above described, thereby to cause the vertical line to be extended downwards. When the paper is fed to a position whereat the paper reverse feed is started, the vertical line key is depressed again so as to print the vertical line.
Accordingly, vertical lines extended in two printing lines do not become one continuous vertical line unless a series of key operations, such as those described above, are completed. In order to extend the vertical line further, the foregoing series of key operations must be repeated one after another. Therefore, to obtain a vertical line without a break, which may be necessary in preparing tables or the like, printing of such a line requires a complex set of operations in conventional typewriters. Thus, working efficiency is low, for example when preparing tables.